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Magnetised CRT

I have a Goodmans 19" (I think) CRT TV which is used mainly for gaming (Xbox). If very light colours are displayed on it for much more that a minute, the purity will start to degrade. Let's say a racing game is being played, the car takes up most of the screen, and is light silver. After about a minute, the right of the car will be pink and the left will be green. This would suggest that it's magnetised by some external source but a similar thing happens to the 21" downstairs, but less extensively. It is not all that noticeable on most games/programmes but I have just bought a game that has almost entirely white menus and within a minute the menu is half red half green. As soon as darker colours are displayed, the distortion goes away. Also, if a very still image is displayed for a while, the same thing happens, even with darker colours. Switching off, degaussing and getting the image moving again all make it fade away, but only temporally. Any ideas?

Reply to
Lewis
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Well the first obvious question is, are there any magnetic sources near these sets? Speakers, other stereo or computer components etc?

Reply to
Rick

This makes me think that you may have some unshielded or poorly shielded speakers sufficiently close to the CTR to influence it. If you're using some external speakers try placing them away from the monitor. If the internal speakers are doing this... I had a 27" Samsung once that use to do that. I took it apart got rid of throw those speakers and install new ones with a better magnetic shield. They happened to be exactly like the speakers I collected from one of those computer monitors with speakers inside....

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Reply to
Main Account

If it's only light (bright) colors, I'd lean more towards doming - heating of the shadowmask causing local changes in purity. Turn down the brightness.

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Reply to
Sam Goldwasser

well it sure is NOT magnetisim, that would always pe present, i suggest this could be shadow mask doming. This is localised distortion of the shadow mask caused by the electron beam heating it. see

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for more.

kev

Reply to
that parrot chap

Call some service shops and see if they remember how to set purity on the older RCAs (some SFS were like that too). It invloves two identical disk magnets and getting the CRT up to full operating temperature.

Other than that you could just turn the contrast down.

JURB

Reply to
ZZactly

being

but

is

while,

degaussing

Sounds like the shadow mask is doming, try turning down the contrast.

Reply to
James Sweet

Hi again, sorry I've been away so long, the doming idea sounds about right because when it displays dark colours it fades away again. I now remember turning the contrast up hugely and brightness up a bit for Halo 2 as it was very dark. I'll try putting it down a bit. Thanks for all the answers.

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is

Reply to
Lewis

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